1. Field of the Invention
The present invention relates to a resin-sealing mold for encapsulating a semiconductor device by sealing a semiconductor element in a molding resin, a method of encapsulating a semiconductor device in a resin using the resin-molding mold, and a method of releasing the resin-sealed semiconductor device from the mold.
2. Description of the Related Art
FIG. 7 is a cross-sectional view that shows a conventional resin-sealing mold of a semiconductor device. FIG. 8 is a cross-sectional view that shows a mold-releasing state of the conventional resin-sealing mold of a semiconductor device. In FIGS. 7 and 8, a semiconductor resin package 51 is formed as follows: A semiconductor element 22 is installed on a lead frame 21 with the semiconductor element 22 being connected to the lead frame 21 through a bonding wire 23, and this is sealed with mold resin 29 set on a plunger 30.
Moreover, the upper mold of the resin-sealing mold of semiconductor device is constituted by an upper-mold cavity insert 24a having a plurality of cavities 36a, a cull insert 26, an upper-mold retainer 27a including the upper cavity insert 24a and the cull insert 26, an elastic post 25 installed between an upper-mold backing plate 34a and the upper-mold retainer 27a, an eject pin 28, an eject rod 31 and an upper-mold frame 35a. 
The eject pin 28 has one end sandwiched between an upper-mold ejector plate 32a and an upper-mold pressing plate 33a with the other end communicating with the upper-mold cavity 36a. Here, the eject pin 28 penetrates the upper-mold retainer 27a and the upper-mold cavity insert 24a. The eject rod 31 is attached to the upper-mold ejector plate 32a. The upper-mold frame 35a allows the upper-mold retainer 27a and the upper-mold backing plate 34a to engage each other.
Moreover, the lower mold of the resin-sealing mold of a semiconductor device is constituted by an lower-mold cavity insert 24b having a plurality of cavities 36b, a lower-mold retainer 27b that has a built-in chamber 11 and includes the lower-mold cavity insert 24b, an elastic post 25 installed between a lower-mold backing plate 34b and the lower-mold retainer 27b, an eject pin 28, an eject rod 31 and an lower-mold frame 35b. 
The eject pin 28 has one end sandwiched between a lower-mold ejector plate 32b and a lower-mold pressing plate 33b with the other end communicating with the lower mold cavity 36b. Here, the eject pin 28 penetrates the lower-mold retainer 27b and the lower-mold cavity insert 24b. The eject rod 31 is attached to the lower-mold ejector plate 32b. The lower-mold frame 35b allows the lower-mold retainer 27b and the lower-mold backing plate 34b to engage each other. The plunger 30 and a molding resin 29 are placed inside the chamber 11. Next, an explanation will be given of a resin-sealing method of a semiconductor device. A frame assembly, which has a semiconductor element 22 and a bonding wire 23 attached to the lead frame 21, is arranged on the lower-mold cavity 36b of the lower-cavity insert 24b placed on the upper surface of the lower mold. Here, the upper and lower resin-sealing molds are preliminarily maintained at a high temperature by heaters, not shown.
Next, molding resin 29 is loaded into the chamber 11. The upper mold of the resin-sealing mold and the lower mold of the resin-sealing mold are clamped together so that the upper-mold cavity insert 24a and the lower-mold cavity insert 24b sandwich the lead frame 21. The plunger 30 is raised so that the molten molding resin 29 in the chamber 11 is injected into both of the upper-mold cavity 36a and the lower-mold cavity 36b through a runner 37. Thus, a semiconductor resin package 51, which is a resin-sealed semiconductor device, is formed.
Next, the semiconductor resin package 51 is maintained (cured) in this state for a predetermined time so as to be cured. Thereafter, the upper mold of the resin-sealing mold and the lower mold of the resin-sealing mold are opened, and the sequence proceeds to a mold-releasing process; however, the semiconductor resin package 51 is stuck to either the upper-mold cavity 36a or the lower-mold cavity 36b due to the adhering strength of its resin, with the result that it is difficult to release the package 51 from the mold.
Then, as the upper mold of the resin-sealing mold is raised, an upper-mold external driving means (not shown) pushes the eject rod 31 out. The eject rod 31, thus pushed out, allows the eject pin 28 attached to the ejector plate 32a to penetrate the retainer 27a and the cavity insert 24a, thereby pressing the upper face of the semiconductor resin package 51. The semiconductor resin package 51 has its upper face pushed by the eject pin 28, and is released from the upper mold of the resin-sealing mold.
Next, the external driving means (not shown) pushes the eject rod 31 out. The eject rod 31, thus pushed out, allows the eject pin 28 attached to the ejector plate 32b to penetrate the retainer 27b and the cavity insert 24b, thereby pressing the lower face of the semiconductor resin package 51. The semiconductor resin package 51 has its lower face pushed by the eject pin 28, and is released from the lower mold of the resin-sealing mold.
Since the conventional resin-sealing mold is arranged as described above, it requires a number of eject pins. The eject pin needs a great amount of time in its boring process with high precision and pin outer-diameter machining process, resulting in an increase in mold manufacturing costs and an lengthened manufacturing time. Moreover, because of limitations in the package designing, the resin-molding process has to be carried out with the tip of the eject pin protruding from the bottom face of the cavity in order to absorb dimensional errors of parts such as the cavity insert, retainer and eject pin; therefore, this structure tends to cause the inner semiconductor element, bonding wire and other parts to expose to the outside of a thin package that has been demanded in recent years. Furthermore, the conventional resin-sealing mold fails to absorb deviations in the frame thickness, causing burrs to be generated on the periphery of the semiconductor resin package and in the vicinity of the cull section.
The present invention has been devised to eliminate the above-mentioned problems, and its objective is to provide a resin-sealing mold for a semiconductor device which can reduce the molding costs and shorten manufacturing time as well as reduce damage to packages by eliminating a number of ejecting pins and having, consequently, a simplified structure. Moreover, another objective is to provide a resin-sealing mold for a semiconductor device which can accommodate deviations in the thickness of a lead frame and, consequently, eliminate thin burrs that tend to occur on the periphery of the semiconductor resin package and in the vicinity of a cull section. Furthermore, still another objective is to provide a method of resin-sealing a semiconductor device which is suitable for the resin-sealing mold. Still another objective is to provide a method of releasing a resin-sealed semiconductor device from the mold.
The present invention has been devised to achieve the above-mentioned objectives, and the resin-sealing mold of a semiconductor device of the first preferred mode of the present invention is provided with: two molds, that is, an upper mold and a lower mold, for resin-sealing a semiconductor device installed on a lead frame, the upper and lower molds forming a cavity, wherein: each of the upper and lower molds comprises: a first cavity insert for forming a cavity side face portion; a first elastic post for supporting the first cavity insert; an elastic plate, built in the first cavity insert, for forming a cavity bottom portion; a second cavity insert embedded at a position adjacent to the elastic plate on the side opposite to the cavity; a second elastic post for supporting the second cavity insert; a retainer including the first cavity insert and the second cavity insert; and a backing plate to which the first elastic post, the second elastic post and the retainer are attached, and either one of the upper mold and the lower mold comprises: a cull insert adjacent to the first cavity insert; and a third elastic post for supporting the cull insert, and the other comprises: a chamber embedded in the retainer.
In accordance with the resin-sealing mold of a semiconductor of the first preferred mode of the present invention, the molding process is free from adverse effects due to deviations in the frame thickness and varied precision in the individual molding parts, etc.; therefore, it is possible to completely prevent the generation of thin burrs. Consequently, it becomes possible to improve the quality, to provide stable mold-releasing and transporting processes, to increase the assembling operation rate, and also to improve the productivity.
The resin-sealing mold of a semiconductor device of the second preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that the first cavity insert and the second cavity insert are allowed to move independently from each other.
In accordance with the resin-sealing mold of a semiconductor of the second preferred mode of the present invention, the molding process is free from adverse effects due to deviations in the frame thickness and varied precision in the individual molding parts,. etc.; therefore, it is possible to completely prevent the generation of thin burrs. Consequently, it becomes possible to improve the quality, to provide stable mold-releasing and transporting processes, to increase the assembling operation rate, and also to improve the productivity.
The resin-sealing mold of a semiconductor device of the third preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that the first elastic post for supporting the first cavity insert has an amount of distortion that is greater than the amount of distortion of the second elastic post for supporting the second cavity insert.
In accordance with the resin-sealing mold of a semiconductor of the third preferred mode of the present invention, it becomes possible to easily carry out the mold-releasing process of the semiconductor resin-sealed package.
The resin-sealing mold of a semiconductor device of the fourth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the third preferred mode, is characterized in that upon clamping the molds, the first elastic post is first shortened, and the second elastic post is then shortened, and upon opening the molds, the second elastic post is first stopped from extending, and the first elastic post is then stopped from extending.
In accordance with the resin-sealing mold of a semiconductor of the fourth preferred mode of the present invention, it becomes possible to easily carry out the mold-releasing process of the semiconductor resin-sealed package.
The resin-sealing mold of a semiconductor device of the fifth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that a semiconductor resin-sealing package is released from the mold by distorting the elastic plate.
In accordance with the resin-sealing mold of a semiconductor of the fifth preferred mode of the present invention, it becomes possible to carry out the mold-releasing process of the semiconductor resin-sealed package, without using the eject pins.
The resin-sealing mold of a semiconductor device of the sixth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that: the upper mold has a piping sleeve for injecting compressed air to the elastic plate, and the elastic plate is distorted by the compressed air injected through the piping sleeve so that the semiconductor resin-sealing package is released from the mold.
In accordance with the resin-sealing mold of a semiconductor of the sixth preferred mode of the present invention, it becomes possible to carry out the mold-releasing process of the semiconductor resin-sealed package, without using the eject pins.
The resin-sealing mold of a semiconductor device of the seventh preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that: the chamber has a groove formed in an inner face thereof, and upon opening the molds, the cull insert and a resin inside the chamber are separated from each other by using the groove.
In accordance with the resin-sealing mold of a semiconductor of the seventh preferred mode of the present invention, it becomes possible to carry out the mold-releasing process by using a simple structure.
The resin-sealing mold of a semiconductor device of the eighth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the seventh preferred mode, is characterized in that: a plunger is installed in the chamber, and residual resin inside the chamber is separated from the mold by using the plunger.
In accordance with the resin-sealing mold of a semiconductor of the eighth preferred mode of the present invention, it becomes possible to carry out the mold-releasing process of residual resin by using a simple structure.
The resin-sealing mold of a semiconductor device of the ninth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that the first cavity insert and the cull insert are allowed to move independently from each other.
In accordance with the resin-sealing mold of a semiconductor of the ninth preferred mode of the present invention, the molding process is free from adverse effects due to deviations in the frame thickness and varied precision in the individual molding parts, etc.; therefore, it is possible to completely prevent the generation of thin burrs. Consequently, it becomes possible to improve the quality, to provide stable mold-releasing and transporting processes, to increase the assembling operation rate, and also to improve the productivity.
The resin-sealing mold of a semiconductor device of the tenth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized by comprising: a seal that is placed on either the lower face of the upper mold or the upper face of the lower mold; and a vacuum evacuation hole that allows the lower face of the upper mold or the upper face of the lower mold to communicate with the outside of the resin-sealing mold, wherein, on the way of descending, the upper mold is temporarily stopped so that a sealed space is formed between the lower face of the upper mold and the upper face of the lower mold by the seal, and after a vacuum evacuation has been operated in the sealed space through the vacuum evacuation hole, the mold clamping operation is carried out.
In accordance with the resin-sealing mold of a semiconductor of the tenth preferred mode of the present invention, since unnecessary gaps are eliminated, it is possible to completely prevent the generation of thin burrs.
The resin-sealing mold of a semiconductor device of the eleventh preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that: the lower mold comprises a positioning pin for positioning the lead frame and the upper mold comprises a build-in cleaning pin in a hole that serves as an escape hole for the positioning pin upon clamping the molds.
In accordance with the resin-sealing mold of a semiconductor of the eleventh preferred mode of the present invention, since unnecessary gaps are eliminated, it is possible to completely prevent the generation of thin burrs.
The resin-sealing mold of a semiconductor device of the twelfth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that: each of the upper and lower molds has a piping sleeve for allowing the elastic plate to communicate with the outside of the resin-sealing mold, and the elastic plate is distorted by a vacuum evacuation through the piping sleeve and an injection of compressed air.
In accordance with the resin-sealing mold of a semiconductor of the twelfth preferred mode of the present invention, it becomes possible to carry out the mold-releasing process of the semiconductor resin-sealed package, without using the eject pins.
The resin-sealing mold of a semiconductor device of the thirteen preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that: the first cavity insert and the elastic plate have desired processed films on respective surfaces contacting the semiconductor resin package.
In accordance with the resin-sealing mold of a semiconductor of the thirteenth preferred mode of the present invention, a desired treatment film is placed on the surface of the mold so that it becomes possible to greatly improve the mold-releasing property and abrasion resistant property.
The resin-sealing mold of a semiconductor device of the fourteenth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the third preferred mode, is characterized in that: the lower mold has a piping sleeve for allowing the elastic plate to communicate with the outside of the resin-sealing mold, and the elastic plate is distorted by compressed air injected through the piping sleeve so that the semiconductor resin package is released from the mold.
In accordance with the resin-sealing mold of a semiconductor of the fourteenth preferred mode of the present invention, it becomes possible to carry out the mold-releasing process of the semiconductor resin-sealed package, without using the eject pins.
The resin-sealing mold of a semiconductor device of the fifteenth preferred mode of the present invention, which relates to the resin-sealing mold of a semiconductor device of the first preferred mode, is characterized in that: each of the upper and lower molds has a piping sleeve for allowing the elastic plate to communicate with the outside of the resin-sealing mold, and the elastic plate is distorted by compressed air injected through the piping sleeve so that the semiconductor resin package is released from the mold.
In accordance with the resin-sealing mold of a semiconductor of the fifteenth preferred mode of the present invention, it becomes possible to carry out the mold-releasing process of the semiconductor resin-sealed package, without using the eject pins.
The resin-sealing mold of a semiconductor device of the sixteenth preferred mode of the present invention is characterized by comprising: two molds, that is, an upper mold and a lower mold, for resin-sealing a semiconductor device installed on a lead frame, the upper and lower molds forming a cavity, wherein: each of the upper and lower molds comprises: a first cavity insert for forming a cavity side face portion; a first elastic post for supporting the first cavity insert; a second cavity insert for forming a cavity bottom portion; a second elastic post for supporting the second cavity insert; a retainer including the first cavity insert and the second cavity insert; and a backing plate to which the first elastic post, the second elastic post and the retainer are attached, and either one of the upper mold and the lower mold comprises: a cull insert adjacent to the first cavity insert; and a third elastic post for supporting the cull insert, and the other comprises: a chamber embedded in the retainer.
In accordance with the resin-sealing mold of a semiconductor of the sixteenth preferred mode of the present invention, the molding process is free from adverse effects due to deviations in the frame thickness and varied precision in the individual molding parts, etc.; therefore, it is possible to completely prevent the generation of thin burrs. Consequently, it becomes possible to improve the quality, to provide stable mold-releasing and transporting processes, to increase the assembling operation rate, and also to improve the productivity.
The resin-sealing mold of a semiconductor device of the seventeenth preferred mode of the present invention is characterized by comprising: two molds, that is, an upper mold and a lower mold, for resin-sealing a semiconductor device installed on a lead frame, the upper and lower molds forming a cavity, wherein: each of the upper and lower molds comprises: a first cavity insert for forming a cavity side face portion and a cavity bottom portion; a first elastic post for supporting the first cavity insert; a second cavity insert that is embedded, on a side opposite to the cavity, at a position adjacent to a thin portion forming the cavity bottom portion that is one portion of the first cavity insert; a second elastic post for supporting the second cavity insert; a retainer including the first cavity insert and the second cavity insert; and a backing plate to which the first elastic post, the second elastic post and the retainer are attached, and either one of the upper mold and the lower mold comprises: a cull insert adjacent to the first cavity insert; and a third elastic post for supporting the cull insert, and the other comprises: a chamber embedded in the retainer.
In accordance with the resin-sealing mold of a semiconductor of the seventeenth preferred mode of the present invention, the molding process is free from adverse effects due to deviations in the frame thickness and varied precision in the individual molding parts, etc.; therefore, it is possible to completely prevent the generation of thin burrs. Consequently, it becomes possible to improve the quality, to provide stable mold-releasing and transporting processes, to increase the assembling operation rate, and also to improve the productivity.
The resin-sealing method of a semiconductor device of the eighteenth preferred mode of the present invention uses the resin-sealing mold of a semiconductor device of any one of the first through seventeenth preferred modes.
In accordance with the resin-sealing mold of a semiconductor of the eighteenth preferred mode of the present invention, the molding process is free from adverse effects due to deviations in the frame thickness and varied precision in the individual molding parts, etc.; therefore, it is possible to completely prevent the generation of thin burrs. Consequently, it becomes possible to improve the quality, to provide stable mold-releasing and transporting processes, to increase the assembling operation rate, and also to improve the productivity.
The mold-releasing method of a resin-sealed semiconductor device of the nineteenth preferred mode of the present invention, which uses the resin-sealing mold of a semiconductor device relating to the first preferred mode, is characterized in that the elastic plate is distorted.
In accordance with the mold-releasing method of the resin-sealed semiconductor device of the nineteenth preferred mode of the present invention, it is possible to carry out the mold-releasing process with less damage to the package.
The mold-releasing method of a resin-sealed semiconductor device of the twentieth preferred mode of the present invention, which uses the resin-sealing mold of a semiconductor device relating to the twelfth preferred mode, is characterized in that upon opening the molds, a vacuum evacuation is operated on the elastic plate through the piping sleeve so that the upper mold is released, and compressed air is then injected to the elastic plate through the piping sleeve so that the lower mold is released.
In accordance with the resin-sealing mold of a semiconductor device of the twentieth preferred mode of the present invention, it is possible to carry out the mold-releasing process with less damage to the package.
The mold-releasing method of a resin-sealed semiconductor device of the twenty first preferred mode of the present invention, which uses the resin-sealing mold of a semiconductor device relating to the fifteenth preferred mode, is characterized in that: the pressure of the compressed air is detected, and when the pressure of the compressed air becomes not more than a predetermined value, the injection of the compressed air is stopped.
In accordance with the resin-sealing mold of a semiconductor device of the twenty first preferred mode of the present invention, it is possible to prevent the compressed air from contaminating the clean room.